FAST CORTICOSPINAL SYSTEM AND MOTOR-PERFORMANCE IN CHILDREN - CONDUCTION PROCEEDS SKILL

Transcranial magnetic stimulation and motor performance tests were use d to study the correlation between corticospinal maturation and actual motor performance in a group of young school children (n = 10, mean a ge = 7 years, age range = 6-9 years). The results were compared with n ormal adults (n = 10, mean age = 24 years, age range = 22-26 years). I n children the central conduction time under the preinnervation condit ion of facilitation and the postexcitatory silent period was similar t o that in adults. However, the central conduction time under relaxatio n, the latency jump (defined as the difference between the two preinne rvation conditions), and the stimulus intensity were statistically dif ferent between children and adults (P < 0.01-0.001). Children did not reach the same level of performance as adults in any of the motor perf ormance tasks (simple acoustic reaction time, tapping, ballistic movem ent, tracking, and diadochokinesis) (P < 0.05-0.01), The results indic ate that at an early school age, children already possess mature fast corticospinal pathways able to access spinal motoneurons through the p yramidal tract. However, despite the partially adult-like level of neu ronal maturation, young school children were not able to perform delib erate motor actions with the same proficiency as adults. (C) 1998 by E lsevier Science Inc. All rights reserved.